Modified polyphenylene ether (PPO/PS) ranks together with PC and PC/ABS among the most frequently used amorphous thermoplastics. Its impact resistance is less than that of PC, but its resistance to chemicals and hydrolysis is better. Low moisture absorption and hydrolysis make this material particularly suited to use in water, for example in pumps, seals and water meters.
Depending on the load, reinforced PPO/PS is resistant for a prolonged period of time to temperatures up to 100°C to 120°C, and for short periods up to the glass transition temperature of 140°C. Moisture absorption is particularly low, i.e. 0.1% at 23°C/50% RH and 0.2% when saturated in water at 23°C. For an amorphous material, its chemical resistance is relatively good. PPO/PS is resistant to alkaline substances, diluted acids and alcohol and, to a limited extent, to most aliphatic hydrocarbons, although swelling does occur when the material is immersed. The material is not resistant to aromatic and halogenated hydrocarbons, strong acids, ketones and petrol. Resistance to UV radiation is reasonable, but can easily be improved by means of stabilisers or special carbon black particles.
These rigidity and strength of PPO/PS decrease in step with temperature. Reinforced types provide excellent mechanical specifications at higher temperatures, however. The same applies to the retention of shape, definitely up to temperatures of around 80°C. PPO/PS is an excellent electrical insulator, barely affected by temperature or humidity. The dielectric properties are less frequency- dependent compared with most other thermoplastics.